cppcheck/lib/checkassignif.cpp

195 lines
6.1 KiB
C++

/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2011 Daniel Marjamäki and Cppcheck team.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
// Check for assignment / condition mismatches
//---------------------------------------------------------------------------
#include "checkassignif.h"
#include "symboldatabase.h"
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace
{
CheckAssignIf instance;
}
void CheckAssignIf::assignIf()
{
if (!_settings->_checkCodingStyle)
return;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
{
if (tok->str() != "=")
continue;
if (Token::Match(tok->tokAt(-2), "[;{}] %var% = %var% & %num% ;"))
{
const unsigned int varid(tok->previous()->varId());
if (varid == 0)
continue;
const MathLib::bigint num = MathLib::toLongNumber(tok->strAt(3));
if (num < 0)
continue;
for (const Token *tok2 = tok->tokAt(4); tok2; tok2 = tok2->next())
{
if (tok2->str() == "(" || tok2->str() == "}" || tok2->str() == "=")
break;
if (Token::Match(tok2,"if ( %varid% %any% %num% &&|%oror%|)", varid))
{
const std::string op(tok2->strAt(3));
const MathLib::bigint num2 = MathLib::toLongNumber(tok2->strAt(4));
if (op == "==" && (num & num2) != num2)
assignIfError(tok2, false);
else if (op == "!=" && (num & num2) != num2)
assignIfError(tok2, true);
break;
}
}
}
}
}
void CheckAssignIf::assignIfError(const Token *tok, bool result)
{
reportError(tok, Severity::style,
"assignIfError",
"Mismatching assignment and comparison, comparison is always " + std::string(result ? "true" : "false"));
}
void CheckAssignIf::comparison()
{
if (!_settings->_checkCodingStyle)
return;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
{
if (tok->str() != "&")
continue;
if (Token::Match(tok, "& %num% )| ==|!= %num% &&|%oror%|)"))
{
const MathLib::bigint num1 = MathLib::toLongNumber(tok->strAt(1));
if (num1 < 0)
continue;
const Token *compareToken = tok->tokAt(2);
if (compareToken->str() == ")")
{
if (!Token::Match(compareToken->link()->previous(), "(|%oror%|&&"))
continue;
compareToken = compareToken->next();
}
const MathLib::bigint num2 = MathLib::toLongNumber(compareToken->strAt(1));
if (num2 < 0)
continue;
if ((num1 & num2) != num2)
{
const std::string op(compareToken->str());
comparisonError(tok, op=="==" ? false : true);
}
}
}
}
void CheckAssignIf::comparisonError(const Token *tok, bool result)
{
std::string errmsg("Mismatching comparison, the result is always " + std::string(result ? "true" : "false") + "\n"
"Mismatching comparison. This error message is for example given for such a comparison: ");
if (result)
errmsg += "'(x & 6 != 1)'. The result of 'x & 6' can't be 1 so the result of the comparison is always true";
else
errmsg += "'(x & 6 == 1)'. The result of 'x & 6' can't be 1 so the result of the comparison is always false";
reportError(tok, Severity::style, "comparisonError", errmsg);
}
void CheckAssignIf::multicompare()
{
if (!_settings->_checkCodingStyle)
return;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
{
if (Token::Match(tok, "if ( %var% & %num% ) {"))
{
const unsigned int varid(tok->tokAt(2)->varId());
if (varid == 0)
continue;
const MathLib::bigint num1 = MathLib::toLongNumber(tok->strAt(4));
if (num1 < 0)
continue;
const Token *tok2 = tok->tokAt(6)->link();
while (Token::simpleMatch(tok2, "} else { if ("))
{
// Goto '('
const Token * const opar = tok2->tokAt(4);
// tok2: skip if-block
tok2 = opar->link();
if (Token::simpleMatch(tok2, ") {"))
tok2 = tok2->next()->link();
// check condition..
if (Token::Match(opar, "( %varid% == %num% &&|%oror%|)", varid))
{
const MathLib::bigint num2 = MathLib::toLongNumber(opar->strAt(3));
if (num2 < 0)
continue;
if ((num1 & num2) == num2)
{
multicompareError(opar, tok->linenr());
}
}
}
}
}
}
void CheckAssignIf::multicompareError(const Token *tok, unsigned int line1)
{
std::ostringstream errmsg;
errmsg << "Comparison is always false because otherwise the condition at line "
<< line1
<< " is not false";
reportError(tok, Severity::style, "multicompare", errmsg.str());
}